Beyond the answers - interesting background to this quiz

A capital that has changed hands many times

Vilnius, the answer to our first question, sits at the confluence of the Neris and Vilnia rivers. Over its long history the city has been shaped by Polish, Russian, German and Soviet rule before becoming the capital of an independent Lithuania in the 20th century. Its historic old town is one of the largest surviving medieval cores in northern Europe and is recognised by UNESCO.

The book at the heart of a world religion

The Quran is the central religious text of Islam, which Muslims believe was revealed to the Prophet Muhammad over a period of roughly two decades in the 7th century. It is written in Arabic and is divided into 114 chapters, known as suras. Because of its importance in prayer and recitation, many Muslims around the world memorise the entire text.

A landlocked nation at the crossroads of Africa

Chad, the correct answer to our border question, is a landlocked country in north-central Africa. It meets Libya to the north, Sudan to the east and Niger to the west, along with several other neighbours. Its landscape stretches from Saharan desert in the north to savanna in the south, and Lake Chad, once one of the largest lakes in the world, has shrunk dramatically over recent decades.

The tallest uninterrupted waterfall on Earth

Angel Falls, in Venezuela, plunges from the plateau known as Auyan-Tepui in Canaima National Park. At around 979 metres, it is the world's highest uninterrupted waterfall. It is named after the American aviator Jimmie Angel, who flew over the falls in the 1930s, though indigenous Pemón people had long known the site as Kerepakupai Merú.

A chemical symbol that breaks the pattern

Helium's symbol is He, and it is one of the few elements whose symbol does not obviously match its English name - the name comes from the Greek word for the sun, helios. It was detected in the Sun's spectrum before being found on Earth. Helium is the second most abundant element in the universe, yet it is relatively scarce in our atmosphere.